Night vision devices are widely used in the military to provide soldiers, aviators and sailors with the ability to view objects at night or during other low light conditions. As of late, with the advent of less complicated and .more affordable designs, night vision devices have also become available to the general public. These publicly available consumer night vision devices have a tremendous range of applications including night marine piloting, underwater vision, night security, surveillance, hunting, fishing, navigation and other such night-related or low light activities.
Examples of consumer-oriented night vision devices and the technology associated therewith can be found in U.S. patent application Ser. No. 08/152,193, entitled MONOCULAR NIGHT VISION DEVICE filed on Nov. 13, 1993 and U.S. design patent application Ser. No. 29/014,252, entitled NIGHT VISION MONOCULAR, filed on Oct. 15, 1993, both of which applications are assigned to the ITT Corporation, the assignee herein and filed by the present inventor herein. Each of the applications relates to monocular night vision devices; other examples of consumer night vision equipment can be found in U.S. patent application Ser. No. 08/108,989 entitled NIGHT VISION BINOCULARS filed on Aug. 18, 1993 and U.S. patent application Ser. No. 07/954,006 entitled CONSUMER NIGHT VISION APPARATUS, filed on Sep. 30, 1992, both of which applications are assigned to the ITT Corporation, the assignee herein.
Night vision devices typically include an image intensifier tube that converts infrared energy into visible light. Such night vision devices typically require sophisticated power supplies and circuitry to control the operation of the image intensifier tube and sophisticated optical arrangements that direct infrared energy into the image intensifier and direct visible light away from the image intensifier. Thus, night vision devices are primarily image intensifiers having a response curve that peaks at near-infrared light wavelengths.
One problem associated with night vision equipment is that, in many situations, particularly during dead-of-night activities, there is often an insufficient near-infrared image available from objects on the ground to make maneuvering and navigation possible by means of the night vision device. Shadows and other dark regions which a night vision device user may encounter will also present a problem.
To solve this problem, it is known that an object can be illuminated by a beam of near-infrared light in the same manner as illuminating an object with visible light. So too can shadows and other dark regions be illuminated with a beam of near-infrared light. As such, the near-infrared light beam and the near-infrared light reflected from the object or dark region will be visible to users of the night vision equipment, but will be invisible to the naked eye.
Unfortunately, the solution to the problem of nighttime illumination is not as simple as providing the night vision user with a near-infrared spotlight. This is because the night vision device user, especially in the case of a portable night vision device, will already have at least one of his hands busy with the operation of the night vision device. Chances are the user will require the use of his other hand for accomplishing some other activity, be it stabilization, or operation of another device related to the night viewing task. Thus, a solution is necessary in order that the free hand or hands of the night vision user need not be concerned with an additional activity of focusing the near infrared beam on the dark objects or regions. Moreover, the task of turning an illuminator on and off presents problems in its own rite. That is, activation of an illumination device by a traditional slide switch means requires additional hand manipulations that are usually undesirable.
Another obstacle to supplying night vision illumination is that the power supplies associated with night vision equipment typically cannot accommodate the power drain of an additional device, such as, an infrared illuminator. Image intensifier tubes and control circuitry associated with most types of night vision devices consume power at a fairly rapid rate. This is especially true of portable night vision devices that are battery powered, wherein it is desirable to reduce the draw on the internal battery, so as to maximize night viewing operation and minimize the costs and inconveniences of battery replacement and/or recharging. Accordingly, an illuminating device which draws power from the battery of a night vision device and hastens the depletion thereof is both undesirable and impractical.
It has been suggested in the prior art to use near-infrared laser diodes to act as a spotlight for night vision devices. High power laser diodes have the advantage of being able to produce a relatively bright and concentrated beam, which can be used to illuminate objects at a great distance with near infrared light. A disadvantage of these laser diodes is that they tend to consume a great deal of power and most importantly, the beams produced from laser diodes can be bright enough to harm unprotected eyes at both close and medium ranges. Thus, it can be extremely dangerous to equip night vision devices with high power laser diodes as a source of near-infrared illumination, especially in the case of hand held night vision equipment adapted for consumer use.
It is therefore an objective of the present invention to provide a means for attaching an infrared light source to a night vision device, such that the user need not be concerned with using his or her free hands to operate and focus the light source. It is an additional object of the present invention to reduce the hand manipulations involved in the activation and deactivation of a near infrared light source.
It is further an object of the present invention to provide a means for adapting a near infrared light source to a night vision device, wherein the power drain to the internal battery of the night vision device is eliminated. It is additionally an objective of the present invention to provide a means for attaching a near infrared light source to a night vision device, wherein the light source is not harmful to the naked eye. It is also an object of the present invention to accomplish the above objectives in a cost effective and simplified manner.